Natural gas purification unit



FIG. 1 is a front and left side perspective view of a natural gas purification unit showing our new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a front end elevational view thereof; and

FIG. 6 is a rear end elevational view thereof. 

The ornamental design for a natural gas purification unit, as shown. 